This invention relates, in general, to light emitting diodes (LED), and more particularly, to an electrical contact for a high efficiency LED.
Typically, light emitting diodes have a top and a bottom electrical contact. For a red LED, i.e., one which emits red light, the epitaxial material on the top surface of the structure usually consists of N-type conductivity AlGaAs which has a limited maximum carrier concentration and very low mobility. Therefore the spreading resistance inherent in the device becomes a problem. To enhance the light emission from the light emitting region outside of the electrical contact area a patterned contact is used to spread drive current across the LED surface. However, drive current is wasted underneath the electrical contact area from which light cannot be emitted. Therefore, it would be desirable to provide an LED structure which makes maximum use of the drive current.
Accordingly, it is an object of the present invention to provide an improved electrical contact for a light emitting diode.
An additional object of the present invention is to provide a high efficiency red LED.